Abstract: Achievement in charter schools in Illinois, Indiana, Michigan, Minnesota, Ohio and Wisconsin has not been found to exceed the achievement levels found in traditional public schools, according to a new study funded by the Great Lakes Center for Education Research and Practice. The study compared school-based data of charters with demographically similar, traditional public schools over a five-year period and found that charter schools were not performing at levels that exceed traditional public schools. The authors did find that charter schools are making significant gains in achievement over time and that all of the states in the study had some very strong charters.